Wireless power transfer system in the offing

New York: Imagine charging your cell phone while on an evening walk without any wire or device near you. This 'power in the air' thought has received a big boost with Duke University researchers demonstrating the feasibility of wireless power transfer using low-frequency magnetic fields over distances much larger than the size of the transmitter and receiver.

“What consumers want and expect from a useful wireless power system is the ability to charge a device wherever it is - not simply to charge it without a cable,” said Yaroslav Urzhumov, assistant research professor of electrical and computer engineering at Duke University.

“Previous commercial products like the PowerMat have not become a standard solution exactly for that reason as they lock the user to a certain area or region where transmission works," he added.

The Duke researchers have created a ‘superlens’ that focuses on magnetic fields.

The ‘superlens’ translates the magnetic field emanating from one power coil onto its twin nearly a foot away, inducing an electric current in the receiving coil, said the study published in the journal "Scientific Reports".

This is the first time that such a system has successfully sent power safely and efficiently through the air.

“We have demonstrated that the efficiency of magneto-inductive wireless power transfer can be enhanced over distances many times larger than the size of the receiver and transmitter," said Urzhumov.

"This is important because if this technology is to become a part of everyday life, it must conform to the dimensions of today's pocket-sized mobile electronics," he added.

‘Superlens’ looks like a few dozen giant Rubik's cubes stacked together. Both the exterior and interior walls of the hollow blocks are intricately etched with a spiraling copper wire reminiscent of a microchip. On one side of the ‘superlens’, the researchers placed a small copper coil with an alternating electric current running through it, which creates a magnetic field around the coil.

“It's actually easy to increase the power transfer distance by simply increasing the size of the coils," explained Urzhumov.

Urzhumov and his team want to drastically upgrade the system to make it more suitable for realistic power transfer scenarios such as charging mobile devices or other electrical devices as you move around in your home or in the neighbourhood.